Sensing glucose based on its affinity for concanavalin A on a glassy carbon electrode modified with a C60 fullerene nanocomposite

Recent Insights into Glucose-Responsive Concanavalin A-Based Smart Hydrogels for Controlled Insulin Delivery

Many efforts are continuously undertaken to develop glucose-sensitive biomaterials able of controlling glucose levels in the body and self-regulating insulin delivery. Hydrogels that swell or shrink as a function of the environmental free glucose content are suitable systems for monitoring blood glucose, delivering insulin doses adapted to the glucose concentration. In this context, the development of sensors based on reversible binding to glucose molecules represents a continuous challenge. Concanavalin A (Con A) is a bioactive protein isolated from sword bean plants (Canavalia ensiformis) and contains four sugar-binding sites. The high affinity for reversibly and specifically binding glucose and mannose makes Con A as a suitable natural receptor for the development of smart glucose-responsive materials. During the last few years, Con A was used to develop smart materials, such as hydrogels, microgels, nanoparticles and films, for producing glucose biosensors or drug delivery devices. This review is focused on Con A-based materials suitable in the diagnosis and therapeutics of diabetes. A brief outlook on glucose-derived theranostics of cancer is also presented.

3D CoMoO4 nanoflake arrays decorated disposable pencil graphite electrode for selective and sensitive enzyme-less electrochemical glucose sensors

Three-dimensional (3D) cobalt molybdate (CoMoO₄) hierarchical nanoflake arrays on pencil graphite electrode (PGE) (CoMoO₄/PGE) are actualized via one-pot hydrothermal technique. The morphological features comprehend that the CoMoO₄ nanoflake arrays expose the 3D, open, porous, and interconnected network architectures on PGE. The formation and growth mechanisms of CoMoO₄ nanostructures on PGE are supported with different structural and morphological characterizations. The constructed CoMoO₄/PGE is operated as an electrocatalytic probe in enzyme-less electrochemical glucose sensor (ELEGS), confronting the impairments of cost- and time-obsessed conventional electrode polishing and catalyst amendment progressions and obliged the employment of a non-conducting binder. The wide-opened interior and exterior architectures of CoMoO₄ nanoflake arrays escalate the glucose utilization efficacy, whilst the intertwined nanoflakes and graphitic carbon layers, respectively, of CoMoO₄ and PGE articulate the continual electron mobility and catalytically active channels of CoMoO₄/PGE. It jointly escalates the ELEGS concerts of CoMoO₄/PGE including high sensitivity (1613 μA mM^-1 cm^-2), wide linear glucose range (0.0003-10 mM), and low detection limit (0.12 µM) at a working potential of 0.65 V (vs. Ag/AgCl) together with the good recovery in human serum. Thus, the fabricated CoMoO₄/PGE extends exclusive virtues of modest electrode production, virtuous affinity, swift response, and excellent sensitivity and selectivity, exposing innovative prospects to reconnoitring the economically viable ELEGSs with binder-free, affordable cost, and expansible 3D electrocatalytic probes.

Tunable hierarchical surfaces of CuO derived from metal–organic frameworks for non-enzymatic glucose sensing

A facile thermal treatment is conducted to prepare nanosphere stacking CuO derived from Cu-MOF, which achieves good glucose sensing performance and is expected to be effective for developing non-enzyme and non-invasive glucose sensors.

Ultrasensitive electrochemical detection of Mycobacterium tuberculosis IS6110 fragment using gold nanoparticles decorated fullerene nanoparticles/nitrogen-doped graphene nanosheet as signal tags

Tuberculosis (TB), caused by Mycobacterium tuberculosis (MTB), remains the top fatal infection continuing to threat public health, and the present detection method for MTB is facing great challenges with the global TB burden. In response to this issue, a novel electrochemical DNA biosensor was developed for detecting the IS6110 fragment within MTB. For the first time, the nanohybrid of gold nanoparticles decorated fullerene nanoparticles/nitrogen-doped graphene nanosheet (Au-nano-C₆₀/NGS) directly served as a new signal tag to generate signal response without additional redox molecules and subsequently labeled with signal probes (SPs) to form tracer label to achieve signal amplification. Additionally, a biotin-avidin system was introduced to immobilize abundant capture probes (CPs), further improving the sensitivity of the proposed biosensor. After a typical sandwich hybridization, the proposed electrochemical DNA biosensor was incubated with tetraoctylammonium bromide (TOAB), which was used as a booster to induce the intrinsic redox activity of the tracer label, resulting in a discriminating current response. The proposed electrochemical DNA biosensor shows a broad linear range for MTB determination from 10 fM to 10 nM with a low limit of detection (LOD) of 3 fM. In addition, this proposed biosensor not only distinguishes mismatched DNA sequence, but also differentiates MTB from other pathogenic agents. More importantly, it has been preliminarily applied in clinical detection and displayed excellent ability to identify the PCR products of clinical samples. There is great potential for this developed method to be used in early diagnosis and monitor of TB.

Voltammetric sensing based on the use of advanced carbonaceous nanomaterials: a review

This review (with 210 references) summarizes recent developments in the design of voltammetric chemical sensors and biosensors based on the use of carbon nanomaterials (CNMs). It is divided into subsections starting with an introduction into the field and a description of its current state. This is followed by a large section on various types of voltammetric sensors and biosensors using CNMs with subsections on sensors based on the use of carbon nanotubes, graphene, graphene oxides, graphene nanoribbons, fullerenes, ionic liquid composites with CNMs, carbon nanohorns, diamond nanoparticles, carbon dots, carbon nanofibers and mesoporous carbon. The third section gives conclusion and an outlook. Tables are presented on the application of such sensors to voltammetric detection of neurotransmitters, metabolites, dietary minerals, proteins, heavy metals, gaseous molecules, pharmaceuticals, environmental pollutants, food, beverages, cosmetics, commercial goods and drugs of abuse. The authors also describe advanced approaches for the fabrication of robust functional carbon nano(bio)sensors for voltammetric quantification of multiple targets. Graphical Abstract Featuring execellent electrical, catalytic and surface properies, CNMs have gained enormous attention for designing voltammetric sensors and biosensors. Functionalized CNM-modified electrode interfaces have demonstrated their prominent role in biological, environmental, pharmaceutical, chemical, food and industrial analysis.

Electrochemical nonenzymatic sensing of glucose using advanced nanomaterials

An overview (with 376 refs.) is given here on the current state of methods for electrochemical sensing of glucose based on the use of advanced nanomaterials. An introduction into the field covers aspects of enzyme based sensing versus nonenzymatic sensing using nanomaterials. The next chapter cover the most commonly used nanomaterials for use in such sensors, with sections on uses of noble metals, transition metals, metal oxides, metal hydroxides, and metal sulfides, on bimetallic nanoparticles and alloys, and on other composites. A further section treats electrodes based on the use of carbon nanomaterials (with subsections on carbon nanotubes, on graphene, graphene oxide and carbon dots, and on other carbonaceous nanomaterials. The mechanisms for electro-catalysis are also discussed, and several Tables are given where the performance of sensors is being compared. Finally, the review addresses merits and limitations (such as the frequent need for working in strongly etching alkaline solutions and the need for diluting samples because sensors often have analytical ranges that are far below the glucose levels found in blood). We also address market/technology gaps in comparison to commercially available enzymatic sensors. Graphical Abstract Schematic representation of electrochemical nonenzymatic glucose sensing on the nanomaterials modified electrodes. At an applied potential, the nanomaterial-modified electrodes exhibit excellent electrocatalytic activity for direct oxidation of glucose oxidation.

Mesoporous carbon-containing voltammetric biosensor for determination of tyramine in food products

A voltammetric biosensor based on tyrosinase (TYR) was developed for determination of tyramine. Carbon material (multi-walled carbon nanotubes or mesoporous carbon CMK-3-type), polycationic polymer-i.e., poly(diallyldimethylammonium chloride) (PDDA), and Nafion were incorporated into titania dioxide sol (TiO2) to create an immobilization matrix. The features of the formed matrix were studied by scanning electron microscopy (SEM) and cyclic voltammetry (CV). The analytical performance of the developed biosensor was evaluated with respect to linear range, sensitivity, limit of detection, long-term stability, repeatability, and reproducibility. The biosensor exhibited electrocatalytic activity toward tyramine oxidation within a linear range from 6 to 130 μM, high sensitivity of 486 μA mM(-1) cm(-2), and limit of detection of 1.5 μM. The apparent Michaelis-Menten constant was calculated to be 66.0 μM indicating a high biological affinity of the developed biosensor for tyramine. Furthermore, its usefulness in determination of tyramine in food product samples was also verified. Graphical abstract Different food samples were analyzed to determine tyramine using biosensor based on tyrosinase.